Citations

In this work, the results from our Comb Push Ultrasound Shear Elastography (CUSE) assessment of suspicious breast lesions are presented. The elasticity value of the breast lesions are correlated to histopathological findings to evaluate their diagnostic value in differentiating between malignant and benign breast lesions. A total of 44 patients diagnosed with suspicious breast lesions were evaluated using CUSE prior to biopsy. All patient study procedures were conducted according to the protocol approved by Mayo Clinic Institutional Review Board (IRB). Our cohort consisted of 27 malignant and 17 benign breast lesions. The results indicate an increase in shear wave velocity in both benign and malignant lesions compared to normal breast tissue. Furthermore, the Young’s modulus is significantly higher in malignant lesions. An optimal cut-off value of the Young’s modulus ≥ 80 kPa was observed for the receiver operating characteristic (ROC) curve. This is concordant with the published cut-off values of elasticity for suspicious breast lesions. [This work is supported in part by the grant 3R01CA148994-04S1 and 5R01CA148994-04 from NIH.]

Vibro-acoustography has gained interest in the recent years as a new modality for medical imaging. This method is based on low-frequency vibrations induced in the object by the radiation force of ultrasound. This paper focuses on potential applications of vibro-acoustography in breast imaging, including detection of microcalcifications, detection of arterial calcifications, and soft tissue imaging. In addition, we will briefly discuss our recent results of in vivo breast vibro-acoustography. Future developments and potential impact of vibro-acoustography in breast imaging are also discussed.

Bladder compliance is defined as bladder’s ability to expand in volume without a significant change in pressure. The bladder wall is a multi-layered structure including a muscular layer and fibrous connective tissue. As the percent of connective tissue in the bladder interstitium increases compared to smooth muscle, the bladder becomes more rigid and less capable of expanding during filling. Currently, urodynamic studies (UDS) are considered as the clinical gold standard for bladder compliance assessment. This procedure is invasive and is associated with patient discomfort and is expensive. Ultrasound bladder vibrometry (UBV) is a novel acoustic-radiation-forced-based method for noninvasive assessment of bladder compliance. In UBV, an impulsive acoustic radiation force is focused on the bladder wall (under B-mode ultrasound image guidance) to induce vibrations which may be modeled by as a Lamb wave. High frame rate ultrasound is then utilized to detect the induced waves. This wave motion is then used to estimate the viscoelastic properties and the compliance of the bladder wall. Our results reveal a remarkable agreement between UBV and UDS cystometry measures, suggesting the potential of UBV as a viable clinical tool for the assessment of bladder compliance.

Thyroid cancer is the fastest growing age and gender adjusted cancer in 2011 according the American Cancer Society. The majority of the clinically diagnosed thyroid nodules are benign while less than 5% represent intrathyroidal cancers. Currently, the clinical gold-standard procedure for assessing the thyroid nodules is needle biopsy, a procedure that is associated with significant financial burden as well as pain and risk for patients. Therefore, a noninvasive, affordable, and potentially widely available method to differentiate between benign and malignant thyroid nodules can play an important role in reducing the number of unnecessary biopsies. In this study, we investigate the feasibility of two acoustic radiation force elastography techniques, shear wave dispersion ultrasound vibrometry (SDUV) and comb-push ultrasound shear wave elastography (CUSE imaging), in identifying thyroid nodules (imaging) and differentiating between benign and malignant pathologies based on their elasticity and viscosity (SDUV measurements). Our preliminary results show that the measured shear elasticity and shear viscosity parameters depend on tissue type; hence, these measurements may be utilized to differentiate between healthy normal thyroid tissue, benign nodules, and malignant nodules. Further studies on a large population of patients is required to better evaluate the role of the combination of elasticity and viscosity properties of tissue in differentiating various thyroid nodules.

Vibro-acoustography image is a function of the dynamic characteristics of the object at the vibration (difference) frequency (df). The dynamic characteristic of tissue is closely related to pathology. Therefore, it is important to evaluate image features versus df. Here, the influence of df on breast vibro-acoustography images is studied by scanning human breast at various df values ranging from 20 to 90 kHz. The subjects were chosen from a group of volunteers with different breast abnormalities. Images were compared subjectively to study image features and the appearances of breast lesions versus df. It is demonstrated that having a collection of images of the same tissue at different df values generally provides a better perception of the tissue structure and improves lesion identification. In most cases, higher df resulted in a higher signal-to-noise ratio and thus a higher image quality. Finally, a frequency-compounded images was obtained by calculating the weighted sum of images at different df values. It is demonstrated that image compounding normally improves visualization of breast tissue and abnormalities. [Work supported by NIH Grant EB-00535 and Grant BCTR0504550 from the Susan G. Komen Breast Cancer Foundation. Disclosure: Parts of the techniques used here are patented by MF and JFG.]

Vibro-acoustography is an imaging method based on the sound emitted due to the harmonic motion of tissue induced by the radiation force of focused ultrasound. This paper presents recent progress in vibro-acoustography of human breast. Matching vibro-acoustography and mammography images are acquired using a combined mammography/vibro-acoustography machine. Images of various types of breast masses are investigated and their characteristics features are compared. The study includes malignant masses, benign masses such as fibroadenomas, cysts, calcified lesions, and surgical scars. Image features, such as lesion borders, interior texture, and speculation pattern, are studied. Vibro-acoustography images demonstrate that calcified masses normally show sharp borders, benign noncalcified masses have smooth texture, and, in some cases, malignant masses are characterized with spiculation. These results, which are based on the data collected from an ongoing study, indicate that the above-mentioned image features may be used for differentiation of breast masses. It is noted that more data from a larger population are needed to establish the results in a statistical sense. [Work supported by NIH Grant EB-00535 and Grant BCTR0504550 from the Susan G. Komen Breast Cancer Foundation. Disclosure: Parts of the techniques used here are patented by MF and JFG.]

Vibro-acoustography is an imaging modality that uses ultrasound as the source of energy to explore objects at two ends of the spectrum. Employing two ultrasound beams at slightly different frequencies, this technique produces a highly localized radiation stress field that vibrates the object at the difference frequency. In response, the object produces a secondary acoustic field. This sound, which contains information about the dynamics of the object at the low difference frequency as well as objects characteristics at the ultrasound range, is used to produce an image of the object. This combination makes vibro-acoustography a unique tool to study biological tissues at low and high frequencies simultaneously. Utility of this method has already been demonstrated for a wide range of applications in vitro. In vivo applications of vibro-acoustography have been demonstrated in a recent study on human breast. It has been shown that this technique can produce high quality in vivo images at ultrasound intensities within the recommended FDA limits. Vibro-acoustography may also be used for imaging solids, such as metallic implants. This paper describes recent achievements in vibro-acoustography as well as possible future role of this technology in medicine. [This abstract includes materials patented by MF and JFG.]

Vibro-acoustography is based on audio-frequency harmonic vibrations induced in the object by the radiation force of focused ultrasound. The resulting object vibration produces a hydrophone detectable acoustic emission that is a function of regional dynamic properties of the object at the vibration frequency. The amplitude of the hydrophone signal is mapped into an image that represents the object’s vibro-acoustic response to the radiation force by scanning the focused ultrasound across the object. Contrast in Vibro-acoustography images represent several properties of the object, including the dynamic characteristics at the audio frequency and scattering and absorption properties at the ultrasound frequency. A Vibro-acoustography system has been combined with a stereo-tactic x-ray mammography system for in vivo breast imaging and has been tested on a number of volunteers. Resulting images show soft tissue structures and microcalcifications within breast with high contrast, high resolution, and no speckles. The results have been verified using x-ray mammograms of the breast. The encouraging results from in vitro and in vivo experiments suggest further development of vibro-acoustography may lead to a new clinical breast imaging modality. [Work supported in part by a grant from the Susan G. Komen Breast Cancer Foundation. Vibro-acoustography is patented by MF and JFG.]

Abstract Objective: This paper introduces an alternative non-invasive and non-ionizing breast imaging tool called vibro-acoustography (VA). This method is based on low-frequency harmonic vibrations induced in the object by the radiation force of ultrasound. Contrast in Vibro-acoustography images represent several properties of the object, including the dynamic characteristics at the audio frequency and scattering and absorption properties at the ultrasound frequency. X-ray mammography and ultrasound are the main imaging modality used today for detection of breast lesions. X-ray mammography, however, is ionizing and its sensitivity is greatly reduced in dense breasts. Ultrasound images suffer from speckles or other or artifact that prevents the physician from delineating the mass lesion from the background tissue. Hence, VA may be used as a stand-alone imaging device or as a tool to provide supplementary information to other existing imaging modalities. Materials & Methods: Matching vibro-acoustography and mammography images of human breast are acquired using a combined mammography/vibro-acoustography machine. Images of various types of breast masses are investigated and their characteristics features are compared. Image features, such as lesion borders, interior texture, and speculation pattern, are studied. Results: Resulting images show soft tissue structures, breast lesions and microcalcifications within breast with high contrast, high resolution, and no speckles. The results have been verified using x-ray mammograms of the breast. Vibro-acoustography images demonstrate that calcified masses normally show sharp borders, benign non-calcified masses have smooth texture, and, in some cases, malignant masses are characterized with spiculation. Conclusion: The encouraging results which are based on the data collected from an ongoing study indicate that the above mentioned image features may be used for differentiation of breast masses and suggest that further development of vibro-acoustography technology may lead to a new clinical tool for various imaging applications. Work supported in part by Grant CA121579-01A1from NIH and Grant BCTR#0504550 from Susan G. Komen Breast Cancer Foundation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4047. doi:1538-7445.AM2012-4047